1. Field of the Invention
The present invention relates generally to a control system for an internal combustion engine, such as for an automotive internal combustion engine. More specifically, the invention relates to an engine control system which is applicable for L-Jetronics type control system, in which an engine load representative parameter is generally monitored by means of an air flow meter, for D-Jetronics type control system, in which an engine load representative parameter is generally monitored by means of a pressure sensor monitoring an intake air pressure in an air induction system, and for so-called -N type control system, in which an engine load representative parameter is monitored by means of a throttle valve angle sensor and which can improve transition control characteristics for improving transition response ability, precision in air/fuel ratio, optimizing spark ignition timing and so forth.
2. Description of the Background Art
In one of the typical known engine control system employs an intake air pressure as an engine load representative parameter. A basic fuel supply amount, e.g. fuel injection amount, is derived on the basis of an engine load data derived on the basis of the intake air pressure, and an engine speed data. The basic fuel supply amount is corrected with a various correction coefficients, such as an engine coolant dependent correction coefficient and so forth. By correcting the basic fuel supply amount with correction coefficients, fuel supply amount is derived.
In addition, correction for the basic fuel supply amount is performed in response to acceleration and deceleration demand in engine transition condition. An acceleration and deceleration fuel supply correction coefficient is generally derived on the basis of a magnitude of variation of a throttle valve open angle.
In practice, the correction coefficient for correcting the basic fuel supply amount is derived by multiplying an acceleration and deceleration dependent correction coefficient which is derived by map look-up performed in terms of a throttle valve angular position variation rate; an engine load dependent correction coefficient derived by map look-up in terms of the basic fuel supply amount, an engine speed dependent correction coefficient derived by map look-up in terms of an engine speed; a throttle valve open angle dependent correction coefficient derived by map look-up in terms of a throttle valve open angle and an engine coolant temperature dependent correction coefficient by map look-up in terms of an engine coolant temperature.
Even in such conventional fuel supply control system, an engine acceleration characteristics tends to be degraded due to lag in compensation of required amount of fuel for making the internal periphery of an intake manifold of an air induction system wet. As a result, air/fuel mixture at the initial period in engine acceleration becomes lean to lower engine performance. In addition, the acceleration and deceleration dependent correction coefficient map is difficult to set in a map over all of the engine driving condition. Furthermore, in order to establish correction coefficient map for deriving the acceleration and deceleration dependent correction coefficient, substantial work should be done with respect to each individual engine for achieving precise acceleration and deceleration transition control. This increases cost for establishing the map and whereby cause substantial increase of the overall cost for establishing the control system.